During some operating conditions of an internal combustion engine it is desirable to provide exhaust gas cooling to an exhaust gas recirculation (EGR) loop or extract heat from the exhaust gas to warm the engine coolant. During other conditions, it is desirable to allow exhaust gas flow to downstream components without passing through a heat exchanger and transferring heat to the engine coolant. In previous engines the exhaust system may be designed to direct cooled exhaust gas to both the EGR loop and downstream exhaust components. A valve augmenting the exhaust gas flow from the heat exchanger to the EGR loop and the downstream exhaust components can be provided in these systems. The valve functions to alter the amount of exhaust gas flowing through the heat exchanger. In prior exhaust systems the valve is actuated via a controller and a solenoid or electric motor. Actuating the valve using a controller and a solenoid has several drawbacks, one being the large number of electronics required to wire the actuation system. For instance, an electronic control unit (ECU), wiring leads, wiring harnesses, etc., may be needed to actuate the valve. The actuation electronics may be susceptible to failure from environmental factors, such as water exposure and vehicle as well as engine vibration. Moreover, the electronics may also require calibration and control strategies that are expensive to develop and computationally intensive to deploy in a control system.
As such in one approach, an engine system is provided. The engine system may include an exhaust gas heat exchanger valve including an actuatable valve plate and a valve actuation assembly adjusting the position of the valve plate. The engine system further includes a flow reversal valve positioned in a coolant passage, the flow reversal valve configured to reverse the coolant flow in a flapper coolant conduit to trigger actuation of the mechanical linkage. The flow reversal valve and mechanical linkage enable the valve plate to be passively actuated to avoid the use of a controller for valve actuation, if desired. Consequently, the reliability and longevity of the valve actuation assembly can be increased when compared to electronic actuation systems.
The inventors herein have recognized the above issues and potential options to address them. The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.